The present invention relates to the power generation industry and, more particularly, power generator rotors and methods related to generator rotors.
In a power generation system, a generator rotor is conventionally positioned within a stator to generate power through magnetic induction as the rotor rotates within the stator. As shown in Prior Art FIGS. 2-3, the rotor 60 has a rotor body 61, e.g., substantially cylindrical in shape, and a rotor shaft 68 extending axially through medial portions of the rotor body 61. The rotor body 61 has a plurality of axially-extending slots 64 formed in the outer peripheries of the rotor body 61 and extending inwardly a preselected depth toward the rotor shaft 68. A plurality of coils 66 is positioned in and extends the length of the slots 64. The coils 66 include end windings 65 or end turns positioned to extend outwardly from the slots 64 along the respective end peripheries of the rotor body 61. In two-pole generator rotors, some of the coils 66 are positioned around a north pole and the remaining are positioned around a south pole. Pole cross-over connectors 67 are positioned to underlie the end windings 65 between the rotor shaft 68 and the inner surface of the end windings 65.
In these type of generator rotors 60, for example, axial zone blocks 70, e.g., a single extended block or an inboard block portion 71 and an outboard block portion 72, are positioned between the outer surface of the rotor shaft 68 and underlying the inner surface of the end windings 65 to create a ventilation barrier such as shown in U.S. Pat. No. 5,483,112 by Biseli et al. titled xe2x80x9cRotor End Turn Ventilation Structure.xe2x80x9d This ventilation barrier assists in cooling the rotor 60 during operation, e.g., by creating a low pressure zone separate from a high pressure zone as understood by those skilled in the art, and for particularly cooling the rotor coils. With such air cooled rotors 60, for example, the pole cross-over connectors 67 create a step in the coil or copper surface against which the axial zone blocks 70 are sealing. To account for this step, the axial zone blocks 70 have a notch 77 or recess formed in the upper peripheral surface. This creates an assembly problem, especially on the excitation end of the rotor 60, that requires a jack, e.g., mechanical or hydraulic, to be placed under the end windings 65 which are lifted or xe2x80x9cjacked upxe2x80x9d to provide enough clearance for the axial zone blocks 70 to be inserted. This lifting makes it difficult to install and remove the axial zone blocks 70 after final assembly of the rotor 60 and can cause damage to the end windings 65 which, in turn, hurts performance of the generator rotor 60.
With the foregoing in mind, the present invention advantageously provides a generator rotor of a power generation system having axial zone blocks and methods of using the same which make the axial zone blocks relatively easy to install and remove. The present invention also advantageously provides axial zone blocks and methods of using the axial zone blocks which substantially reduce damage to the end windings caused by lifting or xe2x80x9cjacking upxe2x80x9d the end windings during installation or removal. The present invention further advantageously provides axial zone blocks which are compact, are formed of at least three portions, and which readily fit together to define a single block in combination positioned between the outer surface of the rotor shaft and the inner surface of the end windings of a generator rotor.
More particularly, an axial zone block according to the present invention preferably is adapted to be positioned to overlie a rotor shaft of a generator rotor and to underlie portions of a plurality of end windings and portions of at least one coil pole cross-over connector of the generator rotor to assist in forming low pressure axial zones in the rotor. The axial zone block preferably includes a separate upper block portion adapted to be positioned to underlie and abuttingly contact portions of the at least one coil pole cross-over connector and portions of the plurality of end windings, a separate lower inboard block portion adapted to be positioned to underlie and abuttingly contact an inboard end of the upper block portion, and a separate lower outboard block portion adapted to be positioned to underlie and abuttingly contact an outboard end of the upper block portion and to be positioned adjacent and abuttingly contact an outboard end of the lower inboard block portion.
According to another aspect of the present invention, a power generation rotor is provided which preferably includes a rotor body having a plurality of slots formed therein and a plurality of coils each positioned in one of the plurality of slots. The plurality of coils each preferably have a plurality of end windings extending outwardly from the plurality of slots along respective end portions, e.g., turbine and excitation end portions, of the rotor body. The rotor also preferably has a plurality of coil pole cross-over connectors positioned to underlie portions of the plurality of end windings. A rotor shaft is preferably positioned to extend axially through the rotor body and to underlie the plurality of coils, the plurality of end windings, and the plurality of coil pole cross-over connectors. The rotor shaft preferably has a plurality of spaced-apart axially extending grooves formed in an outer surface thereof. A plurality of axial zone blocks is positioned between the rotor shaft and portions of the plurality of end windings and the coil pole cross-over connectors to assist in forming low pressure axial zones in the rotor. Each of the plurality of axial zone blocks preferably includes a separate upper block portion positioned to underlie and abuttingly contact at least one of the plurality of coil pole cross-over connectors and portions of the plurality of end windings. A separate lower inboard block portion is positioned to underlie and abuttingly contact an inboard portion of the upper block portion and positioned within a portion of one of the plurality of axially-extending grooves. A separate lower outboard block portion is positioned to underlie and abuttingly contact an outboard end portion of the upper block portion and abuttingly contact the inboard block portion and positioned within the same one of the plurality of axially-extending grooves as the inboard block portion. Each of the lower inboard and outboard block portions preferably includes a spring to assist in positioning the corresponding inboard and outboard block portions in the one of the plurality of axially-extending grooves and to underlie the upper block portion.
The present invention also advantageously provides a method of using an axial zone block. The method preferably includes inserting an axial zone block having at least three separate block portions between the outer surface of a rotor shaft and an inner surface of portions of a plurality of end windings of coils of a rotor without the need to use a jack to hoist portions of the end windings. The inserting step, for example, preferably and advantageously can include positioning an upper block portion of an axial zone block to underlie portions of the end windings of the plurality of coils and portions of at least one pole cross-over connector, positioning a separate lower inboard block portion of an axial zone block to underlie an inboard end of the upper block portion, and positioning a separate lower outboard block portion of an axial zone block to underlie the outboard end of the upper block portion and to be adjacent an outboard end of the separate inboard block portion.
Therefore, by inserting each axial zone block into position under the end winding and the pole cross-over connectors without the need to jack up or hoist the end windings, the end winding and pole cross-over connectors are not damaged from the hoisting action required by a mechanical or hydraulic jack. These methods and types of axial zone blocks can thereby save time and required components for rotor assembly or disassembly at an installation site and still be installed in a way that protects the overlying end windings and pole cross-over connectors. Hence, the axial zone blocks and methods advantageously make installation and removal much easier and efficient for construction, installation, or service personnel without reducing the effectiveness of the axial zone blocks to accomplish their intended functions.